This article will help you with how to copy your CMS data file from one computer to another.
This can be useful as an alternative backup method as well. See Setting Backup Location and CD Backup.

Locate your data file on the other computer. (You can find out where it is by opening CMS and clicking on Help>About Chabad Management System.)
Then copy the file to a flash drive, or zip it (right click, and click Send to>Compressed (zipped) folder) and email the zipped file to yourself.

Copy the file off the flash drive, or download it from your email and unzip it to (My )Documents>CMS>Data. (This folder is created during a CMS installation.)
Now, when opening CMS, it'll ask where your data file is. Click on (My )Documents (on the left panel), then open CMS, open Data, and select the CMS (unzipped) file.